This modular computer uses the 40-pin RCBus.
It can run RomWBW, which includes a very good implementation of CP/M and supports a wide range of hardware. It can also run the Small Computer Monitor (SCM).
Both firmware options can be installed at the same time as the memory module has two sockets for FLASH memory chips. A switch selects which firmware is used.
A minimal RCBus “Alpha” computer contains the following parts:
- CPU module (including Z80 CPU, 7.3728 MHz clock, reset and voltage supervisor, status LEDs)
- Memory module (512KB RAM, two 512KB Flash ROMs)
- Serial module (at least one asynchronous serial port)
- Mass storage module (SD or CompactFlash)
- Backplane (40-pin RCBus module sockets, power input)
Minimal RCBus “Alpha” system
A minimal “Alpha” system (SC691) is available as a kit.
Alternatively, an “Alpha” system can be built from the following modules, backplanes and accessories:
| CPU module | |
SC601 | SC601 – Z80 CPU module with clock, reset and voltage supervisor, and 11 status LEDs |
| Memory module | |
SC602 | SC602 – Memory module 512KB RAM and two 512KB Flash ROMs |
| Serial module options | |
SC603 | SC603 – Serial module (Z80 SIO/2) Two asynchronous serial ports with baud rate options |
SC610 | SC610 – Serial module (68B50 ACIA) One asynchronous serial port (115200 baud) |
| SC612 | SC612 – Serial module (68B50 ACIA) One asynchronous serial port with baud rate options |
| Storage module options | |
SC604 | SC604 – Compact Flash card storage module |
SC611 | SC611 – MicroSD card storage module |
SC613 | SC613 – Compact Flash card storage module |
| Backplane options | |
SC671 | SC671 – 40-pin RCBus backplane with 6 vertical slots, 1 horizontal slot, and 5 volt power input |
SC673 | SC673 – 40-pin RCBus backplane with 10 vertical slots, 1 horizontal slot, and 5 volt power input |
SC133 | SC133 – 40-pin RCBus backplane with 11 vertical slots, 1 horizontal slot, and 8-12 volt power input |
| Optional accessories | |
 | SC346 – Serial to USB C adapter |
 | SC302 – Serial to USB mini-B adapter |
 | SC305 – Adapter cable, 6-way, 8″/200mm |
 | SC306 – USB cable, A to mini-B, 18″/500mm |
There are many options to expand a minimal RCBus “Alpha” system.
RCBus “Alpha” add-ons (recommended)
The following add-ons have been tested with the base system above and are recommended.
| SC600 series modules | |
SC603 | SC603 – Serial module (Z80 SIO/2) A system can contain two of these modules giving four serial ports in total |
| SC604 | SC604 – Compact Flash card storage module RomWBW includes full support for this module, but SCM only includes a CP/M loader for CF cards |
SC605 | SC605 – Digital I/O module 8 digital input signals and 8 digital output signals, each with an LED indicator |
SC606 | SC606 – Real time clock module RomWBW includes full support for this module SCM does not include support for a RTC |
SC607 | SC607 – Prototyping module |
SC608 | SC608 – I2C bus master module A system can contain many of these modules |
SC609 | SC609 – Servo controller module A system can contain many of these modules |
| SC610 | SC610 – Serial module (68B50 ACIA) A system can contain two of these modules giving two serial ports in total |
| SC611 | SC611 – MicroSD card storage module |
| SC612 | SC612 – Serial module (68B50 ACIA) A system can contain two of these modules giving two serial ports in total |
| SC613 | SC613 – Compact Flash card storage module RomWBW includes full support for this module, but SCM only includes a CP/M loader for CF cards |
| SC100 series modules | |
SC134 | SC134 – LED output module |
SC137 | SC137 – I2C bus master module |
SC139 | SC139 – Serial module (68B50 ACIA) |
SC142 | SC142 – Power supply module |
SC145 | SC145 – Compact Flash card storage module |
| Backplane extensions | |
SC147 | SC147 – Backplane extension (adds 6 module slots) |
SC141 | SC141 – Backplane extension (adds 12 module slots) |
| Third party modules | |
RC2014 | RC2014 – Digital I/O module 8 LED outputs and 8 push buttons switch inputs |
RC2014 | RC2014 – Compact Flash storage module |
TMSEMU3 | TMSEMU3 – Graphics and terminal module |
RCBus “Alpha” add-ons (not tested)
The following are some of the available add-ons that are expected to work with the RCBus “Alpha” system.
Flock v2 | Flock v2 floppy disk controller and RTC module |
MG005 | MG005 – Speech synthesiser module |
RC2014 | RC2014 – Pi Pico VGA terminal module |
RC2014 | RC2014 – RP2040 VGA terminal module |
RC2014 | RC2014 – LCD driver module |
RC2014 | RC2014 – CH375 USB storage module |
YM/AY Rev 6 | YM/AY Rev 6 – Sound module |
More information
- RCBus description and specification
- SC600 series, 40-pin RCBus (RC2014 compatible)
- SC691 “Alpha” computer system
- RCBus I/O port addresses
Compatibility
This system conforms to the RCBus specification v1.0 for RCBus-2014 (40-pin).
The RCBus “Alpha” system should work with any modules and backplanes that claim to be compatible with the RCBus-2014 specification for the standard 40-pin bus, as long as there are no I/O port address conflicts and no function conflicts.
Notes
- This product is designed for hobby use and is not suitable for industrial, commercial, or safety-critical applications.
- The product contains small parts and is not suitable for young children.
- RomWBW is copyright Wayne Warthen and has been provided free of charge with his permission.
- The Compact Flash interface circuit has been designed by Tadeusz Pycio and reproduced with his permission.
- RC2014 is a trademark belonging to RFC2795 Ltd.
Small Computer Central 